It does depend on the person- some people can feel small differences, some are obliviously to it.

My right leg it 1/2" shorter than my left, and my pedal stroke is best described as "wonky". I don't have any kind of shims or similar to even out the discrepancy. I get by with a high cadence so I'm not stressing my knees, but I definitely feel it when I start adding miles. My left ITB starts complaining, mostly.

One of my friends built a bike for ultra-marathon rides (the Seattle-to-Spokane "Cannonball", STP, etc.). When I looked at it at the end of a one-day STP, he had the splined steel cranks off by one spline, that is, they were set at 175°/185° from each other. He'd never noticed.